1. Field of the Invention
The present invention relates to an image input apparatus, and, more particularly, to an image input apparatus into which a three-dimensional image, as well as a two-dimensional image, can be easily input.
2. Description of the Related Art
In recent years, the processing power of personal computers has dramatically increased. As the processing of image data has become easier, a larger volume of image data is now used in business documents at offices. In view of this, image data now plays a very important role in document presentation.
With such a trend, there is an increasing demand for an easier image data processing technique that enables a person to obtain image data of a document or an object at hand.
Devices for obtaining image data include scanners and digital cameras. A scanner can take a high-resolution image of a paper sheet, but cannot take an image of a three-dimensional object or characters written on the three-dimensional object. Also, the input memory size of a scanner is limited. In addition to this, a scanner takes up a large space, and it is difficult for a person to carry a scanner around. On the other hand, a digital camera can solve the above problems of a scanner, but is relatively poor in resolution. To solve such a problem, there is a method of combining divisional images of an object picked up by a digital camera.
To perform a divisional image pick-up operation, however, a person has to go to great trouble in picking up many images of one object. Also, the image combining process does not necessarily lead to automatic combining of images with high precision. As a solution to this, Japanese Patent Publication No. 8-13088 suggests a method in which an imaging optical system and an image pick-up optical system are moved to pick up divisional images of an image object, and the divisional images are then combined to form a complete image. In this method, the imaging optical system is moved in two axial directions, and the image object is taken as divisional images to be combined into a high-resolution complete image.
Japanese Laid-Open Patent Application No. 9-161043 discloses a document image input apparatus that can obtain a high-precision document image. In this image input apparatus, a separator is detected so as to reduce the number of partial image pick-up operations and the number of image relative location measuring operations. The document image input apparatus is further equipped with a view-point control mechanism that enables automatic divisional image input and matching-up of divisional images. As shown in FIG. 1, the document image input apparatus has a camera 100 attached to a camera control mechanism 101 that can move the position of the camera 100 with respect to each document. With such a structure, divisional image input and matching-up process for divisional images can be easily performed.
Japanese Patent No. 3063099 discloses an apparatus for reading a double-page spread document, such as an opened book, with the read side facing upward. In this apparatus, a light emitting unit emits linear light onto a double-page spread document at a predetermined angle, and the lighted image is picked up so that the apparatus can detect the curvature of the double-page spread document. Based on the detection result, the curvature is corrected. Also, Japanese Laid-Open Patent Application No. 62-143557 discloses a technique for detecting the distance from a document surface, instead of the curvature, and then correcting for the curvature of the document.
In a general method of measuring a three-dimensional object, a predetermined pattern is projected onto an image object, and a trigonometrical survey is conducted based on the distortions of the projected pattern image. For instance, Japanese Laid-Open Patent Application No. 2000-55636 discloses a method in which a stroboscope is employed as a pattern projector unit so that an ordinary camera can be used in an image input apparatus.
However, none of the above conventional methods and apparatuses has a function for inputting three-dimensional information.
As the processing power of personal computers is becoming greater, the processing of image data containing three-dimensional information, as well as conventional image data, is becoming easier, and three-dimensional images seem to be more widely used at offices. Fur such business use, it is preferable to be able to obtain three-dimensional images of documents and three-dimensional objects, as well as two-dimensional images.
Conventionally, image objects are classified into three types of images consisting of document images, book images, and three-dimensional object images. Depending on the type of image, it is necessary to change image pick-up conditions such as magnification and light pattern projection. However, developing such a system entails complicated processes, and, therefore, neither an image input apparatus that can obtain all three types of images, nor any improvements on existing image input apparatuses to obtain all three types of images, has been suggested.